Radio antenna system



Jam. 28, 1941.. H. K. MQRGAN 329,865

RADIO ANTENNA SYSTEM' y Filed July 25,1958

Patented Jan. Z8, 1941 narra stares PATENT OFFICE 2,229,865 RADI ANTENNA SYSTEM Howard if. lilcrgan, Kansas City, Mo., assigner to Transcontinental & Western Air, Inc., lian-.sas City, Mo., a corporation Application .iuiy 25,1938, Serial No. 221,()87 l Claim. (Cl. Z50-33) rihis invention relates to radio antenna Sys- A further important object of the invention tems of the single Wire type, particularly to such is the provision of an antenna system having antennae that are responsive to currents of difaV single Wire antenna with a two-Wire antenna ferent, predetermined frequencies, and which are feeder, Which feeder is electrically connected to remotely located and Wired to a radio receiver the transmission line leading to a remotely poor transmitter. sitioned receiver or transmitter by a transformer The primary object of this invention is to probetween the coils of which is disposed an elecvide an antenna system of the aforementioned trostatic shield for the purpose of preventing any character, the antenna of which is divided into vertically polarized disturbance, or other radiaa plurality of sections between Which is contion, from being conveyed down the concentric l0 nected tuned anti-resonant circuits that serve line with the signal. This said shield is used to as electrical insulators for currents having frea greater advantage With radio receivers than quencies for which the circuits are resonated; with radio transmitters, but its presence does that serve to eliminate standing Waves on the not lower the eiiiciency in the antenna system 15. transmission line feeding or receiving energy from and therefore, it is desirable to include the shield 154 the antenna so that efficient transfer of such whenever the aforesaid transformer is used as a energy will automatically occur without the necesmeans for connecting the antenna feeder or lead sity of employing compensating circuits; and to a concentric transmission line. that serve as means for presenting a constant A yet further aim of the present invention is 2O impedance from the antenna. l to provide an antenna system having a number v120 A yet further aim of the present invention is of anti-resonant circuits which establish a defito provide a radio antenna system having a nite predetermined amount of anti-resonant implurality of sections between which are connected pedance so that the point of feed (point of conresonant, tuned circuits which present high renection between antenna and feed line), may 25, sistance to currents of predetermined frequencies be adjusted in resistance Within reasonable lim- .25 dependent upon the frequency for which the cirits for the most efficient transfer of energy to the cuits are resonated. Atransmission line.

An even further object of the invention is to Specific objects and methods of employing the provide antenna system having exceptionally invention in an antenna system, Will appear durgreat efficiency ateach of a number of predetering the course of the following specification, rekv30 mined current frequencies and including a numferring to the accompanying drawing wherein:

ber of anti-resonant circuits which divide the Figure 1 is a schematic circuit diagram illussingle antenna into a number of sections to the trating one embodiment of the invention. end that no switching in the antenna circuit nor Fig. 2 is a circuit diagram of another embodinetworks at the antenna feed point are required ment of the invention illustrating the use of a 35 to tune the antenna to any one of a number of transformer. frequencies. Fig, 3 is a schematic circuit diagram, similar to It is understood that heretofore, a number of Fig- 1, but illustrating an antenna plOVided for methods of tuning antennae to predetermined four frequencies; and

frequencies have been tried. Some of these meth- Fig. 4 is a schematic illustration of a portion 40 ods included the step of inserting reactance in of an antenna system, showing the: invention as the antenna structure, but the efficiency of such applied to vertical grounded antennae. methods does not approach that of the present The antenna system diagrammatically illusinvention, which contemplates the inclusion in trated in Fig. 1, is constructed for use when two .i5 the antenna system of anurnber of resonant frequencies are employed and the proper choice 45 tuned circuits which are actually electrical insuof the antenna 6 and tuned circuits 8 and l0, lators against currents of certain frequencies. insures that the system will automatically op- Another of the primary objects of this invenerate at the two frequencies as regards the radio tion is the provision of an antenna system, which receiver and transmitter, not here shown, and

5o is connected to a remotely located radio receiver which are located at a remote point and con- 50 or transmitter by a transmission line, having a nected to the same by transmission Wires l2 and non-tuned but closely coupled transformer at the .M that are joined to the two-wire antenna feedpoint of connection between the two-wire aner I6. canna feeder and the concentric transmission Antenna 6 is a single antenna disposed in a 55., line. horizontal plane and the doublet is tuned to two frequencies, one of which is one half an electrical Wave length. The section of antenna 6 designated A-B between circuits 8 and l0, is respon- 8 and I0 are connected.

At another longer` wave length and frequency, the length of antenna C-D is one half an elec- `trical Wave length.

The antenna illustrated in Fig. 2 is in part precisely the same as that shown in the schematic circuit diagram of Fig. 1. Tuned circuits 8 and I are the same and sections A-B and C-D are similar. The antenna feeder wires I6, however, are joined to one coil I 8 of a closely coupled transformer 20, while the other coil 22 thereof is joined to the concentric transmission line 24 leading to a receiver or transmitter located at some remote point.

An electrostatic screen shield 26 is interposed between the primary and secondary coils of transformer for the purpose of preventing any vertically polarized disturbance or radiation from being passed down the concentric transmission lines 24 with the signal. In view of this particular function of the electrostatic screen shield, a valuable element in Tuned circuits 28, 33 and 32, on one side of the double feeder lines 34, and tuned circuits 36,

not desirable. This invention, however, applies to other than horizontal doublets and multi-section antennae of half Wave lengths. Quarter grounded.

All of the resonant tuned circuits heretofore designated by numerals and described as being interposed 1n an antenna, comprise an inductor 54 and a capacitor 56 (Fig. 1).

Raising the impedance of the anti-resonant circuits Will result in lowering the impedance to the transmission line while lowering the impedance of the anti-resonant circuits will result so as to raise or lower the impedance at those points.

It will be obvious to one antenna 'systems made as illustrated and de- Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

In a radio antenna system of the doublet type, a transmission line adapted to be connected to a HOWARD K. MORGAN.

skilled in the art that t 

